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{{short description|Discouragement of use of a technology, feature, design, or practice}}
{{distinguish|Depreciation}}
In several fields, '''deprecation''' is the discouragement of use of some terminology, feature, design, or practice, typically because it has been superseded or is no longer considered efficient or safe, without completely removing it or prohibiting its use. Typically, deprecated materials are not completely removed to ensure legacy compatibility or back up practice in case new methods are not functional in an odd scenario.

It can also imply that a feature, design, or practice will be removed or discontinued entirely in the future.<ref>{{Cite web|url=http://openjdk.java.net/jeps/277|title=JEP 277: Enhanced Deprecation|website=openjdk.java.net|access-date=2018-02-09}}</ref>

==Etymology==
In general English usage, the [[infinitive]] "to [[wikt:deprecate|deprecate]]" means "to express disapproval of (something)". It derives from the [[Latin]] verb ''deprecare'', meaning "to ward off (a [[disaster]]) by prayer". In current technical usage, for one to state that a feature is deprecated is merely a recommendation against using it. It is still possible to produce a program or product without heeding the deprecation.

==Software==
While a deprecated software feature remains in the software, its use may raise warning messages recommending alternative practices. Deprecated status may also indicate the feature will be removed in the future. Features are deprecated, rather than immediately removed, to provide backward compatibility and to give programmers time to bring affected code into compliance with the new standard.

Among the most common reasons for deprecation are:
*''The feature has been replaced by a more powerful alternative feature.'' For instance, the [[Linux kernel]] contains two modules to communicate with [[Microsoft Windows|Windows]] networks: <CODE>smbfs</CODE> and <CODE>cifs</CODE>. The latter provides better security, supports more protocol features, and integrates better with the rest of the kernel. Since the inclusion of <CODE>cifs</CODE>, <CODE>smbfs</CODE> has been deprecated.
*''The feature contains a design flaw, frequently a security flaw, and so should be avoided, but existing code depends upon it.'' The simple [[C (programming language)|C]] standard function <CODE>[[gets()]]</CODE> is an example, because using this function can introduce a [[buffer overflow]] into the program that uses it.<ref>{{cite book
| author = GNU
| title = The GNU C Library
| section = Line Input
| section-url = https://www.gnu.org/software/libc/manual/html_node/Line-Input.html#Line-Input
| publisher = GNU
| url = https://www.gnu.org/software/libc/manual/html_node/
| access-date = 2008-08-02
| quote = Deprecated function: char * gets (char *s). ... The <code>gets</code> function is ''very dangerous'' because it provides no protection against overflowing the string <code>s</code>. The GNU library includes it for compatibility only. You should ''always'' use <code>fgets</code> or <code>getline</code> instead.}}</ref> The [[Java API]] methods <code>Thread.stop</code>, <code>.suspend</code> and <code>.resume</code> are further examples.<ref>{{cite web
| url = http://download.oracle.com/javase/7/docs/technotes/guides/concurrency/threadPrimitiveDeprecation.html
| title = Java Thread Primitive Deprecation
| publisher = Oracle
| access-date = 13 May 2011
}}</ref>
*''The feature is considered extraneous, and will be removed in the future in order to simplify the system as a whole.'' Early versions of the [[World Wide Web|Web]] [[markup language]] [[HTML]] included a <CODE>FONT</CODE> element to allow page designers to specify the [[font]] in which text should be displayed. With the release of [[Cascading Style Sheets]] and HTML 4.0, the <code>FONT</code> element became extraneous, and detracted from the benefits of noting structural markup in HTML and graphical formatting in CSS. Thus, the <CODE>FONT</CODE> element was deprecated in the ''Transitional'' HTML 4.0 standard, and eliminated in the ''Strict'' variant.
*''A future version of the software will make major structural changes, making it impossible (or impractical) to support older features.'' For instance, when [[Apple Inc.]] planned the transition from [[Mac OS 9]] to [[Mac OS X]], it created a [[subset]] of the older system's [[application programming interface|API]] which would support most programs with minor changes: the [[Carbon (API)|Carbon]] library (that has since been deprecated), available in both Mac OS 9 and Mac OS X. Programmers who were, at the time, chiefly using Mac OS 9, could ensure that their programs would run natively on Mac OS X by using only the API functions supported in Carbon. Other Mac OS 9 functions were deprecated, and were never supported natively in Mac OS X.
*''Standardization or increased consistency in naming.'' Projects that are developed over long periods of time, or by multiple individuals or groups, can contain inconsistencies in the naming of various items. These might result from a lack of foresight, changes in nomenclature over time, or personal, regional, or educational differences in terminology. Since merely renaming an item would break backwards compatibility, the existing name must be left in place. The original name will likely remain indefinitely, but will be deprecated to encourage use of the newer, more consistent naming convention. An example would be an [[application programming interface|API]] that alternately used the spelling "color" and "colour". Standardization would result in the use of only one of the regional spellings throughout, and all occurrences of the other spelling would be deprecated.
*''A feature that once was available only independently is now combined with its co-feature.'' An example is [[VLC Media Player]]; VLC used to stand for "VideoLan Client", and a separate "VideoLan Server" was available as its co-feature. Both the client and server became available in the same package and so getting one independently would be impractical.

==Other usage==
An example in [[hardware design]] is omission of [[pull-up resistor]]s on unused inputs to a [[logic gate]]. This practice may have been acceptable in the past, but has become deprecated because faster [[clock speed]]s are likely to induce more [[transient noise]] on input lines, causing hardware [[glitch]]es or malfunctions.

A [[building code]] example is the use of [[Alternate Current power plugs and sockets#Earthing (grounding)|ungrounded ("2-prong") electrical receptacles]]. Over time, these older devices were widely deprecated in favor of safer grounded ("3-prong") receptacles. The older, ungrounded receptacles were still permitted in many places by "[[grandfathering]]" them in existing [[electrical wiring]], while prohibiting them for new installations. Thus, though ungrounded receptacles may still be available for legal purchase in a location where they are obsolete, they would generally be intended only for repairs to existing older electrical installations.

In writing and [[editing]], usage of a word may be deprecated because it is ambiguous, confusing, or offensive to some readers. For example, the words ''sanction'' and ''[[inflammable]]'' may be misinterpreted because they have [[auto-antonym]]ic or self-contradictory meanings; writing style guides often recommend substituting other words that are clearly understood and unambiguous. Some word usages that have acquired different connotations over time, such as ''[[gay]]'' or ''[[colored]]'', may be deprecated as obsolete in formal writing.

In [[technical standard]]s, use of a certain clause may be discouraged or superseded by new clauses. As an example, in the [[Ethernet]] standard [[Institute of Electrical and Electronics Engineers|IEEE]] 802.3-2012, Clause 5 (Layer Management) is "deprecated" by Clause 30 (Management), except for 5.2.4.

The term ''deprecated'' may also be used when a technical term becomes [[Obsolescence|obsolete]], either through change or supersession. An example from [[paleontology]] is the previously deprecated term ''[[Brontosaurus]]''; before being re-recognized as a unique genus,<ref>[https://abcnews.go.com/Technology/brontosaurus-finally-validated-distinct-dinosaur-species/story?id=30134546 Brontosaurus Finally Validated as a Distinct Dinosaur]</ref> it was considered a popular, yet deprecated, name for the genus ''[[Apatosaurus]]''.<ref name=UBD04>{{cite book |last=Upchurch|first=Paul |author2=Barrett, Paul M. |author3=Dodson, Peter |editor=Weishampel, David B. |editor2=Dodson, Peter |editor3=Osmólska, Halszka |title=The Dinosauria |url=https://archive.org/details/dinosauriandedit00weis|url-access=limited|edition=2nd |year= 2004|publisher=University of California Press |location=Berkeley |isbn=0-520-24209-2 |pages=[https://archive.org/details/dinosauriandedit00weis/page/n277 259]–322 |chapter=Sauropoda}}</ref> Some examples of deprecated terms from medicine include ''consumption'' ([[tuberculosis]]), ''grippe'' ([[influenza]]), and ''apoplexy'' ([[stroke]]). In chemistry, the international standards organization [[IUPAC]] (International Union of Pure and Applied Chemistry) has deprecated the term "methyl ethyl ketone", and now recommends using the term "[[ethyl methyl ketone]]" instead.<ref name=iupac2013>{{cite book | title = Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book) | publisher = [[Royal Society of Chemistry|The Royal Society of Chemistry]] | date = 2014 | location = Cambridge | page = 725 | doi = 10.1039/9781849733069-FP001 | isbn = 978-0-85404-182-4}}</ref>

==See also==
*[[Abandonware]]
*[[List of deprecated terms for diseases]]
*[[Obsolescence]]
*[[Orphaned technology]]

==References==
{{reflist}}

==External links==
{{wiktionary|deprecate}}
{{Wiktionary}}
* [http://download.oracle.com/javase/1.5.0/docs/guide/javadoc/deprecation/deprecation.html How and When To Deprecate APIs] from the JDK 5.0 Documentation
* [http://www.winitor.com Detect deprecated functions] A tool that discovers deprecated functions in any Windows native application or library.
{{Use dmy dates|date=March 2017}}

[[Category:Backward compatibility]]

Deprecation - Revision history

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